Tack welding of sections

ABSTRACT

A method and apparatus for tack-welding sections in the form of plates where at least two plates are arranged with the edge of one plate engaging a face of the other to define therewith a pair of corners situated on opposite sides of the edge of the one plate. The plates are continuously fed in the direction of the latter edge while a pair of welding units are reciprocated along paths parallel to this edge. During the time that each welding unit moves in the same direction as the plates it is rendered operable to deposit a tack weld. The structure which reciprocates the pair of welding units maintains them at all times moving in opposed directions so that while one welding unit moves in the same direction as the plates from a given starting location to a given end location the other welding unit is returning from its end location back to its starting location. The speed with which each welding means is moved at least in the same direction as the plates is different from the speed of movement of the plates.

United States Patent Inventor Masaaki Hano Yokohama, Japan Appl. No.61,741 Filed Aug. 6, 1970 Patented Oct. 12, 1971 Assignee Nippon KokanKabushiki Kaisha Tokyo, Japan Priority Aug. 7, 1969 Japan 44/62040 TACKWELDING 0F SECTIONS 9 Claims, 3 Drawing Figs.

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3,061,714 16/1962 'vansivifali 219/127 3,167,636 1/1965 Bosteels 219 1253,291,360 12/1966 Linnander 219 124 Primary Examiner.l. V. TruheAssistant ExaminerL. A. Schutzman Att0mey-Steinberg & Blake ABSTRACT: Amethod and apparatus for tack-welding sections in the form of plateswhere at least two plates are arranged with the edge of one plateengaging a face of the other to define therewith a pair of cornerssituated on opposite sides of the edge of the one plate. The plates arecontinuously fed in the direction of the latter edge while a pair ofwelding units are reciprocated along paths parallel to this edge. Duringthe time that each welding unit moves in the same direction as theplates it is rendered operable to deposit a tack weld. The structurewhich reciprocates the pair of welding units maintains them at all timesmoving in opposed directions :0 that while one welding unit moves in thesame direction as the plates from a given starting location to a givenend location the other welding unit is returning from its end locationback to its starting location. The speed with which each welding meansis moved at least in the same direction as the plates is different fromthe speed of movement of the plates.

TACK WELDING or SECTIONS BACKGROUND OF THE INVENTION The presentinvention relates to welding.

In particular, the present invention relates to tack welding of sectionsin the form of plates which intersect each other in any of a number ofdifferent arrangements so as to form a framework of the plates which areto be tack welded. For example, the invention is applicable to plateswhich intersect each other so as to form in cross section a frameworkhaving an X, H, T, or other angular configuration. There are alreadyavailable various types of apparatus which are capable of operatingautomatically toachieve a mass production during fillet welding ofplates forming frameworks of the above type. When performing operationsof this type it is necessary to situate the fillets at the cornersdefined on opposite sides of an edge of one plate when the latter edgeengages a face of another plate. Before such fillets are automaticallydeposited it is essential at the present time to carry out manual tackwelding operations, and this manual tack welding creates considerabledifficulties because the locations where the welding is carried out aregenerally positioned in such a way that laborious and small-scale minutemanual operations are required. The result is that the labor costs arestill undesirably high, with this situation being aggravated by laborshortages which are frequently encountered in industry.

SUMMARY OF THE INVENTION It is accordingly a primary object of thepresent invention to provide for tack welding of sections which willavoid the above drawbacks.

Thus, it is an object of the invention to provide a tack-welding methodcapable of automatically achieving tack welding which heretoforerequired manual operations.

Furthermore it is an object of the present invention to provide a methodwhich will achieve the required tack welding with a high degree ofefficiency as well as in a fully automatic manner.

It is also an object of the invention to provide for the tackweldingapparatus which will achieve the required results in a fully automaticmanner, providing tack welds of high quality.

. According to the invention the tack-welding method and apparatus isapplied to plates or sections which intersect each other to form aframework which in cross section has an X, H, T, I or otherconfiguration.- One of the plates will have an edge engaging a face ofthe other plate to define at the latter face a pair of corners atopposite sides of the edge of the one plate, and of course the tackwelds are to be deposited in these corners. The pair of plates are fedby a suitable feeding means continuously in the direction of the edge ofthe one plate at a given feed speed. A pair of welding means are locatedadjacent the corners which are to receive the tack welds for depositingtack welds at the corners when the pair of welding means are renderedoperable. The pair of welding means are both reciprocated by a pair ofsuitable reciprocating means, respectively, along paths which areparallel to the edge of the one plate, and only at least during part ofthe movement of each welding means in the same direction as the plates ameans operatively connected to each welding means renders it operable todeposit a tack weld. The pair of welding means are simultaneouslyreciprocated at speeds different from the given feed speed of the platesin mutually opposed directions so that while one welding means movesfrom a given starting location to a given end location the other weldingmeans is returning from its end location to its starting location. Thestarting locations and end locations for both welding means arerespectively situated at the same points along the path of movement of Athe edge of the one plate, and the speed of movement of the pair ofwelding means is different from, preferably slower than, the speed ofmovement of the plates.

BRIEF DESCRIPTION OF DRAWINGS The invention is illustrated by way ofexample in the accompanying drawings which form part of this applicationand in which:

FIG. 1 is schematic illustration of a method and apparatus of theinvention showing in an end view a pair of plates during thetack-welding operations;

FIG. 2 is a schematic fragmentary top plan view of the method andapparatus of the invention; and

FIG. 3 is a schematic transverse sectional elevation on an enlargedscale, as compared to FIGS. 1 and 2, showing details of the method andapparatus of the invention as applied to one welding means.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to the drawings, FIG.1 shows in an end view a pair of sections or plates 1 and 2 which in theillustrated example form a T-shaped framework. The plate I has a loweredge engaging the upper face of the plate 2 so as to define at thisupper face a pair of comers respectively situated at opposite sides ofthe lower edge of the plate 1. These are the corners which willeventually receive the fillet welds. In order to deposit the tack weldsin these comers a pair of welding means 3 and 4 are provided, asschematically shown in the drawings. These welding means are in the formof suitable nozzles of known construction through which, for example,suitable welding rod is fed with a suitable arc being generated to bringabout the deposition of the molten tack welds when the welding means 3,4 are rendered operable by completion of a suitable electrical circuit,as part of the operations which are carried out.

A reciprocating means is operably connected with each welding means 3, 4in order to reciprocate each welding means back and forth from a givenstarting location to a given end location and then on return stroke fromthe end location back to the starting location. The starting locationfor both of the welding means is indicated by the dotted line in FIG. 2,while the end location is indicated by the dotted line 5 for both of thewelding means. Thus, in FIG. 2 the welding means 4 is shown in dot-dashlines fragmentarily at the starting arid end locations and is shown insolid lines proceeding along from the starting toward the end locationin the same direction in which the plates 1, 2 are continuously fed. Onthe other hand the welding means 3 is shown in FIG. 2 in solid linesjust at the moment when it has started to return from its end location 5back toward its starting location 6, where the welding means 3 is shownin dot-dash lines. A feeding means is provided for continuously feedingthe plates 1, 2 in the direction of the lower edge of the plate 1 whichengages the upper face of the plate 2, and the reciprocating means ofthe invention is connected with each welding means in order toreciprocate the latter along a path parallel to the feeding movement ofthe plates 1, 2. The pair of reciprocating means which are operativelyconnected with the pair of welding means are operated in such a way thatwhile one welding means is moving in the same direction as the platesthe other welding means is moving in the reverse or opposed direction. Ameans is operatively connected with each of the welding means to renderthe latter operable only during that time when it is moving in the samedirection as the plates, but the reciprocating means acts on eachwelding means to move the latter at a speed difi'erent from, eitherslower or faster than, the speed of feed of the plates 1, 2. It is thisdifference between the speedof the nozzles and that of the work that istaken into account in order to determine the feeding speed of the platesas well as the reciprocating speed of the nozzles in accordance with thewelding conditions which are in general encountered. The work 1, 2 is ingeneral fed at a speed which is extremely high as compared with thatencountered during conventional welding. For example, the work 1, 2 maybe fed at a speed of 6,000 mm./min., in which case the pair of nozzlesor welding means 3, 4 are moved at a speed of 5,000 mm./min. to 5,500mmJmin.

Thus, the pair of welding means 3, 4 are reciprocated back and forthwhile the work 1, 2 is fed continuously in one direction only, and whenone of the welding means 3, 4 is ready to start its return stroke fromthe end location 5 back to the starting location 6, the operationthereof is terminated, suitable limit switches, timers, or otherelectrical control apparatus, being used in order to form the meanswhich will render each welding means operable only during at least partofjthe time when it moves in the same direction as the work. Thus, whenone of the welding means, the welding means 3, for example, is at theend location 5 ready to return to the starting location 6, the otherwelding means 4 will be at the starting location 6 and will commence itsmovement in the same direction as the work to be rendered operableduring at least part of this movement toward the end location 5. Whenthe welding means 4 reaches the end location 5, the other welding means3 will have reached the starting point 6 and will then start to move inthe same direction as the work while the welding means 4 returns to thestarting location, with welding means 3 at this time being renderedoperable. In this way a series of tack welds such as the tack weld aindicated in FIG. 2 are deposited at the comers defined between thesections or plates 1, 2. It will be noted that with this method the tackwelds at one comer will be out of registry with, respectively situatedbetween, the tack welds at the other corner so that a zigzag formationof tack welds is provided with the apparatus and method of theinvention.

The structure of the invention is shown in FIGS. 1-3 in a generallyschematic manner. The pair of welding means 3, 4 are fixedly carried bysuitable attachment components 7,8, respectively. Thus, referring toFIG. 3, it will be seen that the welding means 3 is adjustably fixed ina suitable sleeve 20 as by a setscrew 22. This sleeve is fixed by anysuitable support 24 onto the attachment component 7. The components 7and 8 are respectively formed with slots which pass verticallytherethrough for receiving extensions 11 and 12, respectively, ofsupporting blocks. Thus, FIG. 3 shows the supporting block 26 whichcarries the extension 11, being fixed to the latter, as by being fonnedintegrally therewith, and of course, the extension 12, received in theslot of component 8, is supported in the same way by a suitableunillustrated block. The block 26 is formed with a central guideaperture which receives a supporting bar 28 on which the block 26 islongitudinally slidable, this bar 28 being supported in any suitablemanner and extending parallel to the direction of feed of the work 1, 2.In addi'tion to this structure operatively connected to each weldingmeans 3, 4, each reciprocating means includes in the illustrfatedexample a pair of sprocket wheels and a chain extending around the pairof sprocket wheels. Thus, FIG. 2 illustrates the pair of sprocket wheels13 and the endless chain 9 of the reciprocating means for the weldingmeans 3, as well as the pair of sprocket wheels 14 and the endless chainfor the reciprocating means operatively connected with the welding means4. As may be seen from FIG. 3, the sprocket chain 9 fixedly carries anupwardly directed pin 30 received in a groove 32 formed at the undersideof the block 26. This groove 32 simply extends transversely of the bar28. Thus, as the chain 9 moves in response to rotation of the sprocketwheels 13, one of which is driven so as to provide rotation in thedirection of the arrow as shown in FIG. 2, the pin 30 will engage theblock 26 to bring about the reciprocation of this block together withall of the structure carried thereby. In the same way an identicalstructure is connected with the welding means 4 in order to reciprocatethe latter.

As has been indicated above, the means for rendering each welding meansoperable may include any suitable limit switches, timers, or the like.FIG. 3 illustrates, for example, an electrically conductive brushcomponent 34 carried by the chain 9 and insulated therefrom, forming,for example, an extension of the pin 30. When the brush 34 moves in thesame direction as the work, it engages a pair of elongated electricalcomponents 36 and 38 which are connected into the circuit for thewelding means 3. This circuit will be completed when the brush 34engages both of the components 36 and 38,

which may be in the form of elongated electrically conductive bars of asuitable length to maintain the welding means 3 operable only for alength of time, or part of the length of time, during which it moves inthe same direction as the work 1, 2. The sprocket wheels 14 are drivenin the direction shown by the arrows in FIG. 2 and bring aboutoperations identical with those provided for the welding means 3 with astructure identical with that shown in FIG. 3, for example, but suitablyoriented with respect to the location of the welding means 4 on the sideof the plate 1 opposite from the welding means 3. The particularreciprocating mechanism illustrated in the drawings for each weldingmeans is but one example of different types of reciprocating means whichmay be provided. For example, it is possible to use fluid-pressurestructures such a piston and cylinder arrangements actuated either byhydraulic or pneumatic pressure. Also it is possible to use rotaryscrews which are rotated first in one direction and then in anotherdirection to coact with suitable nuts which carry the structure in orderto reciprocate the latter. Any other types of well-known reciprocatingmeans may be used.

The feed means for feeding the work is shown in FIG. I as includingupper and lower feed rollers l5, 16 which respectively engage the upperedge of the plate 1 and the lower face of the plate 2 in order tomaintain the lower edge of the plate I pressed against the upper face ofthe plate 2. In addition, the opposed side surfaces of the plate I areengaged by a pair of feed rollers l7, l8, and these rollers 15-18 aredriven so as to bring about a continuous feeding of the work in adirection away from the viewer of FIG. 1.

It is apparent that it a simple matter to change, in an extremelyconvenient way, the pitch or spacing between the successive tack weldssimply by changing the relationship between the speed of feed of thework and the speed of movement of the pair of welding means. Thus, thepitch or spacing between the successive tack welds can be increased ordecreased simply by changing the speed with which the pair of weldingmeans are reciprocated or the speed of movement of the work 1, 2, aslong as the movement of the parts is maintained with a range which willnot undesirably retard or other wise undesirably influence the speedwith which the tackwelding operations are carried out.

Thus, with the method and apparatus of the invention the pair of weldingmeans are simply moved at a speed different from this speed of movementof the work 1, 2 to be rendered operable while moving in the samedirection as the work to provide tack welds at a required spacing fromeach other and in a zigzag pattern with each tack weld on one side ofthe plate 1 being situated between a pair of tack welds on the otherside. As was pointed out above the pair of welding means are renderedoperable to generate welding arcs only when the pair of welding meansmove in the same direction as the work. In this way it is possible tobring about a fully automatic tackwelding method and apparatus, so thattack-welding operations which heretofore have been carried out manuallycan now be carried out automatically. Thus, the problem of laborshortages and high labor costs can be met with the method and apparatusof the invention, while at the same time the work is carried out at ahigh degree of efficiency producing a beautifully finished series oftack welds arranged in a zigzag pattern with all the operations beingcarried out at an extremely high speed.

What is claimed is:

1. In a method of tack welding at least a pair of plates one of whichhas an edge engaging a face of the other plate to define at said face apair of corners at opposite sides of the edge of said one plate, thesteps of feeding said plates in the direction of said edge of said oneplate at a given feed speed, simultaneously reciprocating at speedsdifferent from said feed speed and along paths parallel to said edge ofsaid one plate a pair of welding means for respectively depositing tackwelds at said corners, and rendering each welding means operable todeposit a tack weld only during at least part of the time when eachwelding means moves in the same direction as said plates.

1. In a method of tack welding at least a pair of plates one of whichhas an edge engaging a face of the other plate to define at said face apair of corners at opposite sides of the edge of said one plate, thesteps of feeding said plates in the direction of said edge of said oneplate at a given feed speed, simultaneously reciprocating at speedsdifferent from said feed speed and along paths parallel to said edge ofsaid one plate a pair of welding means for respectively depositing tackwelds at said corners, and rendering each welding means operable todeposit a tack weld only during at least part of the time when eachwelding means moves in the same direction as said plates.
 2. In a methodas recited in claim 1, the reciprocation of said pair of welding meansbeing carried out in a manner maintaining the pair of welding means inmovement in opposite directions with one of the pair of welding meansmoving from a given starting location to a given end location in thedirection of feed of the plates while the other welding means moves in areverse direction from the end location back to the starting location.3. In a method as recited in claim 2 and wherein the plates arecontinuously fed.
 4. In a method as recited in claim 3 and wherein thepair of welding means are continuously reciprocated.
 5. In a method asrecited in claim 4 and wherein the pair of welding means arereciprocated at a speed slower than said given speed at least during thetime when each welding means moves in the same direction as the plates.6. In a method as recited in claim 5 and wherein said given feed speedfor the plates is on the order of 6,000 mm./min. and said pair ofwelding means are each moved at least in the same direction as saidplates at a speed of 5,000-5,500 mm./min.
 7. In an apparatus forautomatically tack welding at least a pair of plates one of which has anedge engaging a face of the other to define at said face a pair ofcorners on opposite sides of said edge, a pair of welding meansrespectively located adjacent said corners for depositing tack welds atsaid corners when the pair of welding means are rendered operable, feedmeans for feeding said plates in the direction of said edge of said oneplate, a pair of reciprocating means Respectively connected operativelyto said pair of welding means for respectively reciprocating the latterat speeds different from the feed speed of said plates along pathsextending parallel to said edge, and means coacting with each weldingmeans for rendering the latter operable only during at least part of thetime when each welding means moves in the same direction as the plates.8. The combination of claim 7 and wherein said pair of reciprocatingmeans are respectively connected operatively with said pair of weldingmeans for simultaneously reciprocating the latter in mutually opposeddirections so that when one welding means moves in the same direction assaid plates the other welding means moves in a direction opposite to thedirection of movement of the plates.
 9. The combination of claim 8 andwherein said pair of reciprocating means respectively reciprocate saidpair of welding means between starting and end locations which are atthe same points longitudinally along the path of movement of said platesfor both welding means.